Python String index() Method
The Python string index() method can search a given string object's substring. It returns the index number or position of the substring(occurs first) in the given string. It raises a ValueError If the substring does not exist in the subject string.
This index() method accepts three parameters.
|substr(required)||This substring to be searched in subject string.|
|start(optional)||It is an integer value specifying the index position to start the search. If not specified, the default value 0 is taken.|
|end(optional)||It is an integer value specifying the index position where to end the search. If not specified, -1 value is taken, and mean full string length is searched|
The lowest index position of the occurrence of the string within another string. If the given string is not found, It raises a ValueError.
In the following example, the occurrence of 'i' is searched within the string, and the index always starts with 0. Hence it will return 4 as a result.
# Python example of the index() method. str = "Nothing is impossible!!!" result = str.index("i") print(result)
If no start and end arguments are assigned.
name = 'Tutorials Nation' result = name.index('Nation') print("Substring 'Nation' occurrence found at", result)
The following example checks, If the given string is found. If the substring is not found, the index() method raises the ValueError.
name = 'Tutorials Nation' try: result = name.index('web') except ValueError: result = -1 if result != -1: print("The substring is found.") else: print("The substring is not found.")